Hyperspectral imaging is known to reveal details impossible or difficult to see by the human eye, such as for instance tissue differences in a human. In hyperspectral imaging an image is taken of an object in one or more wavelength bands where at least one wavelength band is at least partly invisible to the human eye or at least very difficult to see. This image is then converted into a visible image, which image is provided in visible light to a viewer. Hyperspectral imaging can be based both by spectrally selective illumination (i.e. illumination an object with light in a certain wavelength band) and by spectrally selective filtering prior (i.e. using a filter that transmits only light in a certain wavelength band) to image capture. In both cases image processing is required to generate a resulting image revealing the structure contrast of interest.
In such a system conventionally a hyperspectral image (e.g. image extending beyond the visible spectrum) is taken and the result is shown on a display screen. Sitting behind the display screen the viewer, interested in not or hardly visible details of the object under observation, can study the image on the screen in visible light as it would appear in for instance UV light, or in IR light.
Although using a screen is a very useful technique, the possibilities are limited. It has been proposed to project a hyperspectral image on a studied object, for instance in R. K. Miyake, H. D. Zeman, F. H. Duarte, R. Kikuchi, E. Ramacciotti, G. Lovhoiden, C. Vrancken, “Vein imaging: A new method of near infrared imaging where a processed image is projected onto the skin for the enhancement of vein treatment”, Dermatologic, Surgery, vol. 32, pp. 1031-1038, 2006. The projection is performed with a laser projector.
It is difficult, if not near impossible, using the known technique to provide a good sharp projection wherein the projection coincides to a relatively high degree of alignment unless the object, in the known prior art the skin, is stationary and to a high degree flat.
It is an object of the invention to provide a system and a method that allows directly seeing hyperspectral details of an object under observation and in correct alignment.